Strenuous exercise increases apoptosis of intestinal lymphocytes (IL). Bovine lactoferrin (bLf), a protein found in milk products, affects lymphocyte apoptosis and the expression of TH1 and TH2 cytokines.
The purpose was to determine whether bLf affects apoptosis and TH1 (tumor necrosis factor α) and TH2 (interleukin-10) cytokine expression in IL of mice given strenuous exercise.
Female C57BL/6 mice (n = 89), given three bouts of treadmill exercise, were killed either immediately, 24 h after the last bout, or before initiation of exercise; within exercise conditions, mice were fed control (0% bLf) or bLf-supplemented (2% bLf) diet for 12 d until sacrifice. IL were enumerated, and apoptosis and cytokine expression were determined by Western blot analysis; markers of stress (corticosterone and iso-prostanes) were measured in the plasma by radioimmunoassay and direct immunoassay.
Exercise increased IL loss (P < 0.05) and the expression of caspase 3 (P < 0.001), heat shock protein 70 (P < 0.01), and interleukin-10 (P < 0.05) in mouse IL; bLf did not alter these responses. However, bLf reduced tumor necrosis factor α expression in mouse IL (P < 0.05), possibly through decreased nuclear factor κB expression (P < 0.05) in the supplemented group.
Dietary bLf does not affect IL apoptosis after exercise but may confer intestinal protection through changes in cytokine expression, independent of exercise.
Department of Health Studies and Gerontology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, CANADA
Address for correspondence: Laurie Hoffman-Goetz, Ph.D., FACSM, Department of Health Studies and Gerontology, Faculty of Applied Health Sciences, University of Waterloo, 200 University Ave W, Waterloo, Ontario, Canada N2L 3G1; E-mail: firstname.lastname@example.org.
Submitted for publication November 2007.
Accepted for publication December 2007.